Contact fuze



Jan. 29, 1957 L M ANDREWS ET AL 2,779,287

CONTACT FUZE Filed Nov. l, 1951 2 Sheets-Sheet l :Eff-5- Jan. 29, 1957L.. M. ANDREWS ET AL 2,779,287

CONTACT FUZE Filed Nov. 1, 1951 2 sheets-sheet 2 ,2 22 INVENTORJ;Laurence JV[..An;fr-ews [6a ,5 /5 /la BYJacnh Rahn-law United StatesPatent O CONTACT FUZE Laurence M. Andrews and Jacob Rabinow, TakomaPark,

Md., assignors to the United States of America as represented by theSecretary of the Army Application November 1, 1951, Serial No. 254,429

11 Claims. (Cl. 102-81.2)

(Granted under Title 35, U. S. Code (1952), sec. 266) The inventiondescribed herein may be manufactured and used by and for the Governmentof the United States of America for governmental purposes without thepayment to us of any royalties thereon or therefor.

The present invention relates to a fuse for aircraft cluster bombs whichwill detonate upon impact.

More particularly, the present invention relates to a fuse for use inthe cluster type bomb dropped from aircraft, and which is designed tobecome armed upon being subjected to a strong, sustained air blast todetonate upon impact.

ln the use of cluster bombs which are dropped from aircraft to detonateupon impact, it is desirable that the fuse for each bomb in the clusterbe so designed that it will be armed by sustained rapid air travel, butwill remain unarmed if subjected to a continued, relatively weak airblast or by a strong air blast which is of short duration.

Also desirable is a fuse which is designed so that it will not becomeaccidently armed by ordinary handling or if dropped. However shouldaccidental arming occur, the provision of a precautionary measure togive visual indication of such arming, and to prevent assembly into thecluster in armed condition, is also an advantageous feature.

It is therefore an object of this invention to provide a fuseincorporating all the aforementioned desirable features.

It is also an object of this invention to provide a fuse for a clusterbomb which will become armed, and which will remain locked in armedposition, by a strong, sustained air blast maintained for the requiredtime, but which will not become armed when subjected to a continued,relatively mild, air blast, -ory a strong air blast of short duration.

It is also an additional object of this invention to provide a fusehaving an impeller and vanes responsive to air pressure to actuate agear train to move an arming block and primer from first safe positionto second armed position.

It is also a further additional object of this invention to provide afuse including a precautionary measure to prevent the assembly of thefuse incorporating bomb into a cluster, and which will give a visualindication that the fuse is armed.

With these and other objects in view which will become apparent as thefollowing specification develops, reference is made to the accompanyingdrawing wherein:

Figure 1 is a View of a plurality of bombs as they may be mounted in abomb bay;

Figure 2 is a diagrammatic section taken on line 2-2 of Figure 1 andshowing the arming block and safety pins schematically;

Figure 3 is a longitudinal section taken on line 3-3 of Figure 5;

Figure 4 is a forward elevation of the fuse looking toward the rear ofFigure 3 (position and relation of parts as during descent of bomb);

2,779,287 Patented Jan. 29, 1957 Figure 5 is a transverse section takenon line 5-5 of Figure 3;

Figure 6 is a section taken on line 6-6 of Figure 3;

Figure 7 is a longitudinal section of the fuse in an armed position, butwith parts rearwardly positioned as when the bomb has been subjected toa short, strong air blast;

Figure 8 is a longitudinal section of the fuse in armed and operatedposition;

Figure 9 is a fragmentary longitudinal section similar to Figure 3showing a modification of the fuse, and

Figure 10 is a view showing another modification of the fuse.

Referring to Figure 1, a support 1 within the bomb bay has mountedthereon a plurality of cups 2, for receiving the tail iin assembly 3which forms no part of the present invention and is therefore not shownin detail but which will be brieiiy described. The fin assemblycomprises an end plate 3a, an opposing end plate 3b to which is securedby brackets a plate 3c joined in any convenient manner to a bomb casing4 containing incendiary or other material. Secured between plates 3a and3b are a plurality of shafts 3d upon which are mounted vanes springbiased to pivot outwardly when the bomb is released from cup 2. In theiroutwardly extended position the vanes will afford stabilization and dragto the bomb. However in stowed or folded position the tins are confinedto a. diameter approximately equal to that of the bomb, thus the bombsin a cluster may nest closely together without danger of the tins of onebomb entangling those of an adjacent bomb.

Referring to Figure 3, the fuse body is provided with a hexagonallyshaped housing 5 having a reduced rear portion 5c which is counterboredas at 5d. The reduced portion 5c is externally threaded at 5a so that itcan be screwed into container 4 shown in Figure 1. The reduced portionis also internally threaded as at 5b to receive within the counterbore5d a booster cup '7 containing the booster S. Also fixedly disposedwithin the counterbore 5d, contiguous with and directly forward ofbooster 8 is a block 9 having an axial bore 9a to receive a cylindricalcapsule 10 of soft easily fracturable metal containing detonatingmaterial 10a. Formed .integral with hexagonal housing 5 at the forwardend is a reduced hollow cylindrical portion 11 having a plurality ofholes 12 formed in its walls to permit the escape of air when the bombis descending. The inner peripheral wall of cylinder 11 is inwardlystepped forwardly as at 11a to form a shoulder 11b for ixedly supportinga spider 13 having a centrally located bearing 14, and journaled in thisbearing is a rearwardly axially extending impeller shaft 15 upon whichis mounted for rotation, in radial alinement with holes 12, a turbinerotor or impeller 16 having forwardly depending vanes 16a (see Figures 3and 4). The rearmost extremity of shaft 15 is pointed as at 15a to forma striking pin. Apertures 13a are formed between the legs of spider 13to permit an air blast to impinge against impeller 16.

Counterbore 5d in the reduced rear portion 5c extends forwardly intohousing 5 and is substantially closed oif by an inwardly extendingportion or partition 40 of housing 5 to provide a space d1 toaccommodate arming block 30, security pin 6 and other moving parts in amanner to be subsequently described. A forwardly stepped substantiallycylindrical axial bore 42 of larger diameter than bore 5d is formed inthe remaining portion of hexagonal housing 5 forward of partition 40. Aring 19 forming a rear shoulder 19a and forward shoulder 19b is securedin any convenient manner to the inner wall of the forward half sectionof bore 42. A disc shaped flat plate 13 loosely rests on shoulder 19bfor axial movement in bore 42 and a correspondingly heavier at platedisc 27 rests on shoulder 19a and is also axially movable arrasar withinbore 42. Plate 18 is pressed forwardly by a concave bevel washer typecomparatively weak spring 20 extending between the forward surface ofplate 27 and the rear surface of plate 18. Plate 27 is in turn pressedforwardly by a pair of contiguous relatively strong concave bevel typewasher springs 2S pressed between the forward surface of partition 4t)and the rear surface of plate 27. Shaft 15 is also journaled in acentrally located hole 18a in plate 18 and a centrally located hole 27ain plate 27. Springs 20, 28 and partition 40 are also centrallyapertured to permit striking pin 15a to reciprocate therethrough.

The portion of shaft 15 extending between plate 18 and impeller 16 is ofincreased diameter and is form-ed as a worm gear 17 (see Figure 6).Meshing with worm 17 is a gear 22 formed on the inner end of a shaft 21which extends laterally in a direction normal to shaft 15 and isjournaled in brackets 21a secured to and depending forwardly from plate18. Rigidly mounted on the outer end of shaft 21 is a second Worm gear23 which meshes with a gear 24 mounted on the forward end of a pinionshaft 25 disposed parallel to and eccentric of shaft 15, and extendingrearwardly in the fuse housing. Pinion shaft 25 having an elongatedpinion gear 25a maintained thereon, is journaled in plate 18 and isreceived in apertures formed in plate 27 and partition 40, a portion ofthe pinion shaft and gear also extending into space 41 formed betweenthis partition and block 9. A locating pin 26 is rigidly secured in abore formed in partition 40 and extends through and slidably ts holes inplates 1S and 27 to prevent these plates from rotating relative to oneanother and to the housing 5.

Referring to Figures 3 and 5, housing 5 is provided with a lateralrecess 44 axially coextensive with and in open communication with space41 formed between block 9 and partition 40. An arming block 30 extendsbetween block 9 and partition 40 and is slidable therebetween so that inunarmed position the end of the block rests against a closing plug 34screwed into the wall of housing to close off recess 44 and to permiteasy assembly of the parts. Arming block 30 is biased into unarmedposition or to the right as seen in Figures 5 and 7 by a spring 31 whichsurrounds pin 6, said pin being secured in any convenient manner toblock 30 to extend laterally outwardly through a bore 45 formed inhousing 5 diametrieally opposite recess 44. Arming block 30 is providedwith an axial bore 36a for receiving an easily rupturable capsule 32containing a primer or detonating substance 33. In unarmed positioncapsule 32 is out of axial alinement with detonating substance a incapsule 10, and striking pin a. When the fuse is armed the twodetonating capsules and pin 15a are in axial alinement so that uponimpact the pin 15a pierces the bottom wall of capsule 32 to set oft` theprimer. Arming block 30 is provided with a rack 29 on the face adjacentto shaft 25 to engage the pinion gear 25a thereupon when the fuse hasbeen subjected to su'icient air pressure to move the fuse parts towardarmed position. A roller 29a secured to block 9 and partition 40 ispressed against the face of block 3i) opposite to the side provided withrack 29 to hold arming block 30 in line when it is moving.

The action of the fuse will best be understood by considering Figures 3,7 and 8. Figure 3 shows the fuse in unarmed position and before the fusehas been subjected to any air pressure. In this position plates 18 and27 are pressed forwardly by springs 20 and 28, and shaft 15, impeller 16and pinion shaft 25 are urged to their forwardmost positions so thatpinion gear 25a is out of engagement with rack 29. Block 30 is biased tothe extreme right as seen in Figures 5 and 7 and capsule 32 is out ofaxial alinement with capsule 10 and striking pin 15a. As can readily beseen in Figure 5, pin 6 does not protrude beyond the periphery ofhousing 5, thus facilitating the arrangement of several of the fusedbombs into a cluster as previously explained, and as illustrated in .4Figures 1 and 2. It is to be noted at this time that spring 2t) iscalibrated so that an air blast of predetermined strength is required tocompress this spring to permit the impeller, shaft and associated geartrain, plate 18 and shaft 25 to move rearwardly. Spring 28 on the otherhand is an extremely strong spring which will compress only on impact toenable pin 15a to strike the primer in capsule 32. If a moderate airstream passes through the openings in spider 13, as for example, when abomb be cornes accidently dislodged While it is being loaded into aplane and drops to the ground to be subjected to the air blast frompropellers on adjacent planes, this air stream will act upon the vanesand impeller 16 causing it and the associated gear train to rotate. Noaction will occur as a result of this rotation since spring 20 is notcompressed and pinion gear 25a does not engage rack 29.

If on the other hand the blast is suiciently strong to compress spring20, the associated parts will move rearwardly to cause pinion gear 25ato engage rack 29, and impeller 16 will rotate thereby rotating pinionshaft 25 to move block 30 to the left as seen in Figure 5, against thebias of spring 31, and towards armed position. This position may best betermed semi-armed and is clearly illustrated in Figure 7. However sincethe air blast is of a shorter duration than that predetermined timerequired to completely arm the fuse, at the termination of such airblast, spring 20 will return pinion shaft 25 to disengaged position andspring 31 will return block 30 to unarmed position.

It is readily apparent therefore, that only a strong, sustained airblast prolonged for the requisite time, as when a bomb is dropped, willcause block 30 to be driven by the rack, pinion and associated geartrain until capsules 32, 10 and striking pin 15a are in axial alinement.The continued air blast will jam the gear train to retain the block inarmed position so that upon impact, spider 13 is collapsed, spring 28 iscompressed and shaft 1S is driven rearwardly in the fuse, causingstriker pin 15a to detonate primer 32, detonator 10 and booster 7 tocause the bomb to function. Figure 8 illustrates the fuse in completelyarmed position and after impact. Since in completely armed position pin6 protrudes outwardly from housing 5, if the fuse were to becomeaccidently armed in handling and preparatory to arranging into acluster, this condition would give visual indication to the handler thatthe fuse is armed, and would also preclude nesting of the bombs into acluster until the fuse was again rendered safe.

Figure 9 is a modification of the fuse illustrated in Figures 1-8wherein shear pins 28a are substituted for spring 28. These pins may bemade of metal sufficiently strong to withstand all air pressures and toshear off onlty. in response to strong impact as when the target 1s 1t.

Figure l0 is another modification of the fuse wherein coil springs 28bare substituted for spring 28 to act in like manner as spring 28 orshear pins 28a.

Other modications and alterations of the structure which has beendisclosed herein for purposes of illustration will be apparent to oneskilled in the art, and it is obvious that the same may be made withoutdeparting from the spirit and scope of the invention as defined in thefollowing claims.

We claim:

1. A fuse including an arming block transversely slidable from safe toarmed position in a bore located rearwardly in said fuse, a detonatoreccentrically disposed in said block when in safe position, a vanedimpeller journaled in the nose of said fuse for transverse rotation andaxially rearward translation in response to a blast of air, means insaid fuse resiliently biasing said vaned impeller in a direction opposedto said rearward translation, means in said fuse rearwardly axiallymovable integrally a predetermined distance with said impeller againstthe bias of said resilient means and in response to a blast of air toengage said arming block, and a gear train in said fuse actuated by therotation of said impeller and operatively connected to said blockengaging means for moving said block and detonator to armed position inresponse only to a sustained air blast.

2. The fuse as recited in claim l and including a rearwardly directedring pin axially disposed in the nose of said fuse, said firing pin alsocomprising a shaft for said impeller, and means in said fuse normallyrestraining said firing pin and said vaned impeller against movementbeyond said perdetermined distance and actuable upon impact when saidfuse is armed to permit said firing pin to forcibly contact saiddetonator.

3. The fuse as recited in claim l wherein said arming block moving meanscomprises a pinion shaft, a pinion integral with said pinion shaft, anda rack on said arming block engageable by said pinion.

4. The fuse as recited in claim 1 wherein said arming block moving meanscomprises a pinion shaft, a pinion integral with said pinion shaft, anda rack on said arming block engageable by said pinion, a rearwardlydirected tiring pin axially disposed in the nose of said fuse, saidtiring pin `also comprising a shaft for said impeller, and means in saidfuse engaging said firing pin and said vaned impeller and actuable uponimpact when said fuse is armed to permit said firing pin to forciblycontact said detonator.

5. The fuse as recited in claim 4 wherein said gear train comprises afirst worm on said tiring pin, a transverse shaft having a gear on oneend to engage said first worm, and a second worm on the other end ofsaid transverse shaft meshing with the pinion on said pinion shaft.

6. The fuse as recited in claim 5 and including a security pin fixed tosaid arming block on one end and having its other end extending into atransverse bore formed in said fuse, said pin having a length toprotrude beyond the outer peripheral wall of said fuse only when saidfuse is armed, and a helical spring surrounding said pin and abuttingsaid block to normally bias said block in safe position.

7. In a fuse having a body symmetrical about a longitudinal axis, therebeing an elongated axial bore formed in said body, an arming system forsaid fuse comprising an arming block supported rearwardly in said borefor transverse movement from safe position to armed position, saidarming block having an eccentric longitudinal bore for receiving adetonator, a vaned impeller journaled in op posed transverse walls inthe nose of said fuse for transverse rotation and rearward axialmovement in response to a blast of air, resilient means in saidelongated bore biasing said vaned impeller in a direction opposed tosaid rearward movement, a rack on said arming block, a rearwardlydirected pinion shaft disposed forwardly in said elongated bore, anelongated pinion integral with said pinion shaft, means providing aconnection between said impeller and said pinion shaft whereby saidpinion shaft moves integrally in a rearward direction with said impellera predetermined distance against the bias of said resilient means toengage said rack in response to an air blast, and a gear train actuatedby rotation of said impeller and operatively connected to said pinionshaft to rotate said last named shaft and move said detonator and armingblock to armed position in response only to 1a sustained blast of air.

8. rIhe fuse recited in claim 7 and including a rearwardly directedfiring pin axially disposed forwardly in said elongated bore, saidtiring pin also forming a shaft for said impeller, and means in saidfuse normally restraining said firing pin and said impeller againstmovement beyond said predetermined distance, and actuable upon impactwhen said fuse is armed to permit said ring pin to forcibly contact saiddetonator,

9. The fuse recited in claim 8, wherein said gear train comprises aiirst worm on said firing pin, a transverse shaft having a gear on oneend to engage said rst Worm, and a second worm on the other end of saidtransverse shaft meshing with the pinion on said pinion shaft.

10. The fuse as recited in claim 9, and including a security pin fixedto said arming block on one end and having its other end extending intotransverse bore formed in said body, said pin having a length toprotrude beyond the outer peripheral wall of said. body only when saidfuse is armed, and a helical spring surrounding said pin and abuttingsaid block to normally urge said block to safe position. i

1l. In a fuse, a body having reduced rearward and forward portions and acentral hexagonal portion, there being a longitudinal bore formed insaid body, an arming block mounting an eccentrically disposed primersupported rearwardly in said central hexagonal portion and transverselyslidable from safe to armed position, a vaned impeller journalled insaid forward reduced portion for transverse rotation and axiallyrearward movement in response to a blast of air, means in said bodyresiliently biasing said vaned impeller in a direction opposed to saidrearward movement, means in said body rearwardly axially movableintegrally with said impeller a predetermined distance against the biasof said resilient means and in response to a blast of air to engage saidarming block, a gear train in said body actuated by the rotation of saidimpeller and operatively connected to said block engaging means formoving said [block and detonator to armed position in response only to asustained air blast, a security pin fixed to said block and movabletherewith through a transverse bore in said hexagonal portion, said pinadapted to lie entirely within said body when said fuse is unarmed, ahelical spring surrounding said pin and biasing said block to safeposition, said pin adapted to extend beyond the periphery of said bodywhen said fuse is armed to give a visual indication of said arming.

References Cited in the tile of this patent UNITED STATES PATENTS1,726,325 Varaud Aug. 27, 1929 1,842,467 Woodberry Ian. 26, 19322,407,844 Moriarty Sept. 17, 1946 2,409,205 Graumann Oct. 15, 19462,420,237 Girouard May 6, 1947 2,447,941 Imber et al Aug. 24, 19482,450,910 ORear Oct. 12, 1948 2,644,398 Rabinow July 7, 1953

